Process for making lincomycin and analogs thereof and novel compounds obtained thereby

ABSTRACT

Lincomycin is formed by tosylating methyl 1-thio- Alpha -Dgalacto-octopyranoside to form methyl 6-O-(p-toluenesulfonyl)-1thio- Alpha -D-galactopyranoside, acylating the resulting compound to form the peracylate, replacing the tosyl group with iodine to form peracylated methyl 6-deoxy-6-iodo-1-thio- Alpha D-galactopyranoside, replacing the iodo group by a nitro group to form peracylated methyl 6-deoxy-6-nitro-1-thio- Alpha -Dgalactopyranoside, treating the latter with acetaldehyde and sodium methoxide to form methyl 6-deamino-6-nitro- Alpha thiolincosaminide, reducing the latter with lithium aluminum hydride to form methyl Alpha -thiolincosaminide, and acylating the latter with trans-1-methyl-4-propyl-L-2-pyrrolidinecarboxylic acid. By substituting other aldehydes and/or other 1-thio- Alpha -D-galactopyranosides, analogs of lincomycin are obtained.

United States Patent Magerlein 1 Sept. 19, 1972 [72] Inventor: Barney J. Magerlein, Portage, Mich.

[73] Assignee: The Upjohn Company, Kalamazoo,

Mich.

[22] Filed: May 6, 1970 [2]] Appl. No.: 35,256

Related US. Application Data [63] Continuation-impart of Ser. No. 867,362, Oct.

17, 1969, abandoned.

[52] US. Cl. ..260/2l0 R, 260/999 [51] Int. Cl ..C07c 47/18 [58] Field of Search ..260/2l0 R [56] References Cited UNITED STATES PATENTS 3,475,407 10/1969 Birkenmeyer ..260/2l0R Primary Examiner-Lewis Gotts Assistant Examiner-Johnnie R. Brown Attorney-George T. .lohannesen and John Kekich [57] ABSTRACT Lincomycin is formed by tosylating methyl l-thio-a-D- galacto-octopyranoside to form methyl 6-0-(ptoluenesulfonyl l -thio-a-D-galactopyranoside, acylating the resulting compound to form the peracylate, replacing the tosyl group with iodine to form peracylated methyl 6-deoxy-6-iodo-l-thio-a-D-galactopyranoside, replacing the iodo group by a nitro group to form peracylated methyl 6-deoxy-6-nitro-lthio-a-D-galactopyranoside, treating the latter with acetaldehyde and sodium methoxide to form methyl 6- deamino-6-nitro-a-thiolincosaminide, reducing the latter with lithium aluminum hydride to form methyl a-thiolincosaminide, and acylating the latter with trans- 1 -methyl-4-propyl-L-2-pyrrolidinecarboxylic acid. By substituting other aldehydes and/or other 1- thio-a-D-galactopyranosides, analogs of lincomycin are obtained.

4 Claims, No Drawings PROCESS FOR MAKING LINCOMYCIN AND ANALOGS THEREOF AND NOVEL COMPOUNDS OBTAINED TI-IEREBY CROSS REFERENCE TO RELATED APPLICATION This application is a continuation in part of my copending application Ser. No. 867,362, filed Oct. 17, 1969, and now abandoned.

BRIEF SUMMARY OF INVENTION This invention relates to a process for making lincomycin and its analogs and novel compounds obtained thereby. The following sequence is illustrative:

CHzOH CHzOH HO I Step 1 HO MESH H, OH OH OH H I I OH H D-galactose methyl l-thio-a-D- galactopyranoside l TsH Step 2 CHZOTS CHzOTs AcO Step 3 HO OAc OH \I Me I SMe 0A0 IV OH III methyl 2,3 4-tri-O-acetyla-D-galactopyranoside 0H VIII 0H VII methyl a-thiolincosaminide methyl fi-deamino-fi-nitroand 7-epimer (R=methyl) a-thiolincosaminide and 7-epimer (R =methyl) PHAH Step (trans-l-methyli-propylproline) PHANH- HO OH \I l/ SMe 0H IX Lincomycin and 7epimer =methy1) On exposing the mixed epimers IX to chromatography or liquid-liquid countercurrent extraction, for example adsorption chromatography, partition chromatography, or Craig countercurrent distribution, or like separation process, the two isomers, for example lincomycin (lXa) and 7-epilincomycin, methyl 6,8- dideoxy-6-( transl -methyl-4-propyl-L-2-pyrrolidinecarboxamido 1 -thio-D-erythro-a-D-galactooctopyranoside and methyl 6,8-didoexy-6-(trans-lmethyl-4-propyl-L-2-pyrrolidinecarboxamide 1 -thio- L-threo-a-D-galacto-octopyranoside, are separated.

The several steps generally are carried out by procedures already known in the art. The mercaptolysis (step 1) is a known process. The tosylation (step 2) is atypical, however, because only the 7-O-hydrogen is replaced. This is accomplished by the use of the stoichiometric amount of tosyl chloride (not more than 5 percent excess) and keeping the temperature low, say between about minus 5 C. and about plug 5 C. Pyridine or like tertiary base can be used as the solvent and acid acceptor. The acylation (step 3) of the 2-, 3-, and 4-hydroxyls of the sugar can be effected by acetic anhydride or like acid anhydride in pyridine in the usual manner or by other known acylation procedures. The replacement of the tosyl group by iodine (step 4) is effected with sodium iodide in acetone in the usual manner, and'the replacement of the iodine by nitro (step 5) is effected by sodium nitrite in dimethylformamide to which phloroglucinol may be added to reduce side reactions. Advantageously an excess of sodium nitrite is used, and the reaction is effected with gentle heating say to between about 50 C. and about C. Step 6 is an aldol-type condensation in which the ahydrogen is activated by the nitro group instead of by a carbonyl, as in the Sowden-Fischer synthesis. Step 7 is a standard lithium aluminum hydride reduction and step 8 is an acylation by known acylation procedures, for example, those disclosed in U.S. Pat. No. 3,380,992.

In place of the transl-methyl-4-propylproline, there can be substituted other L-2-pyrrolidinecarboxylic acids, also in accordance with the disclosure in U.S. Pat. No. 3,380,992, whereby analogs of lincomycin and its 7-epimer are obtained. Also in place of acetaldehyde (step 6), there can be substituted other aldehydes for example formaldehyde, propionaldehyde, butyraldehyde, benzaldehyde, or substituted aldehydes for example salicylaldehyde, tolualdehyde, methylpentanal, nitrobenzaldehyde, or vanillin. For example if formaldehyde is substituted, 8-norlincomycin, 6-(transl-methyl-4-propyl-L-2-pyrrolidinecarboxamido)-1- thio-L-glycero-a-D-galacto-heptopyranoside, is obtained. Similarly when propionaldehyde is substituted, there are obtained 8-homolincomycin, methyl 6,8,9- tridoxy-6-(trans-1-methyl-4-propyl-L-2-pyrrolidinecarboxamide l -thio-D-erythro-a-D-galactononopyranoside, and 8-homo-7-epilincomycin, methyl 6,8 ,9-trideoxy-6-( transl -methyl-4-propyl-L-2- pyrrolidinecarboxamido)-1-thio-L-threo-a-D-galactononopyranoside.

Ac in the above compounds represents a carboxacyl protective group as commonly used in sugar chemistry. Ordinarily, it will be acetyl or benzoyl, but can be any equivalent protective carboxacyl group. Whenever desired the Ac groups can be removed by base catalyzed hydrolysis. Me is methyl or other lower-alkyl DETAILED DESCRIPTION OF THE INVENTION The invention can be more fully understood by reference to the following example in which the solvent ratios are by volume and the other parts and proportions are by weight unless otherwise specified.

EXAMPLE Lincomycin and 7-Epilincomycin Part A: D-Galactose dimethyldithioacetal CHzOH SMe HO i

SMe

- To a solution of 25 g. of D-Galactose (I) in 100 ml. of cone. hydrochloric acid cooled to 0 C. was added 25 g. of methanethiol. The reaction mixture was permitted to warm to room temperature and stirred for 17 hours. The addition of 250 ml. of ethanolcaused crystallization of D-galactose dimethyldithioacetal (X) which was collected by filtration, washed and dried. A yield of 13.5' g. (35 percent yield) of crude D-galactose dimethyldithioacetal (X), m.p. 157-l59 C. was thus obtained. Recrystallization of 1 g. of this material from methanol afforded 850 mg. of D-galactose dimethyldithioacetal (X), m.p. 160-163 C., [04],, +6 (MeOH, c=0.35 The mother liquors were pooled and reserved for part B.

An excess of lead carbonate was added to the alcohol filtrate, and the mixture was filtered. The filtrate was concentrated under vacuum to a small volume at which point crystals formed. After cooling, the crystals were collected,- washed and dried. The crude crystals of D- galactose dimethyldithioacetal (X) weighed 7.7 g. Recrystallization of this product from methanol gave 4.6 g. of D-galactose dimethyldithioacetal (X), m.p. 161-l64 C.

Part B: Methyl 1-thio-a-D-galactopyranoside (II) The mother liquors from the crystallization of D- galactose dimethyldithioacetal in part A-lwere con centrated. This residue of 16.3 g. was acylated in the usual manner with 50 ml. of acetic anhydride and 50 ml. of pyridine. The crude acetates, weighing 20.7 g.,

mixture was treated with Dowex-50(I-I a crosslinked polystyrene nuclear sulfonic acid cation exchanger in the acid form, until neutral and then chromatographed over 500 g. of slilica gel using chloroformzmethanol (2:1) as the solvent system. After a forerun of 650 ml., successive SO-ml. fractions were collected. Fractions 16 through h 26 were pooled and evaporated to dryness methyl l-thio-a-D-galactopyranoside II).

Part C: Methyl 6-O-(p-toluenesulfonyl)- l-thio-a-D- galactopyranoside (III) At 0 C. 5.65 g. of tosyl chloride (p-toluenesulfonyl chloride) was added to a solution of 6.0 g. of methyl 1- thioa-D-galactopyranoside (II) in 30 ml. of pyridine. The solution was maintained at 0 C. overnight and evaporated to dryness under vacuum. The residue was stirred with dilute HCl. The crystals of crude methyl 6- O-(p-toluenesulfonyl)- 1 -thio-a-D-galactoside (III) were collected by filtration and dried to give 5.54 g. m.p. l32-142 C. A portion was recrystallized from methanol. The melting point of methyl 6-O-(ptoluenesulfonyl)-l-thio-oz-D-galactoside (III) proved to be highly dependent on the rate of heating. When heated at the rate of 2 C./min., methyl 6-O-(pto1uenesu1fony1)- 1 -thio-a-D-galactoside (III) melted 139-140 C., sinter 136 C. Its [(11 in pyridine was +l83, c=l.0.

Analysis:

Calcd. for C I-b 0 82 C, 46.14; H,5.53;S, 17.60. Found: C, 46.17; H, 5.86; N, 17.28. Part D: Methyl 6-O-(p-toluenesulfonyl)-l-thio-a-D- galactopyranoside 2,3,4-tri-O-acetate IV) Acylation of 4.54 g. of methyl 6-O-(p-toluenesulfonyl)-l-thio-a-D-galactoside (III) with 13 ml. of pyridine and 13 ml. of acetic anhydride at room temperature for 17 hours. yielded 4.9 g. of glassy methyl 6- NO-(p-toluenesulfonyl--D-galactopyranoside 2,3,4-tri- O-acetate (IV).

Analysis:

Calcd. for CgoHg OmSg;

Mol. Wt. 490. Found: M''' 490. (Molecular ion, mass spec.)

Part E: Methyl 6-deoxy-6-iodo-l-thio-a-D-galactopyranoside 2,3,4-tri-O-acetate (V) A solution of 19.5 g. of crystalline methyl 6-O-(ptoluene-sulfonyl)-1-thio-a-D-galactopyranoside 2,3 ,4- tri-O-acetate (IV) and 15 g. of NaI in 200 ml. of acetone was heated in a glass bomb at C. for 7.5 hours. After cooling, the sodium tosylate, which weighed 6.3 g. (82 percent, was removed by filtration. The acetone was distilled under vacuum. The residue thus freed of acetone was partitioned between methylene chloride and dilute sodium bisulfite solution and chromatographed over 1.1 kilograms of silica gel using chloroform-methanol (6:1 as the solvent system. After a forerun of 2.1 liters, successive SO-ml. fractions were collected. Fractions 2 through 12 were pooled and evaporated to dryness yielding 9.29 g. of methyl 6- deoxy-6-iodol -thio-a-D-galactopyranoside 2,3 ,4-tri- O-acetate (V) (51.2 percent) as a glass.

Part F: Methyl 6-deoxy-6-nitro-l-thio-a-D-galactopyranoside 2,3,4-tri-O-acetate (VIAc) CHgNOz A solution of 9.29 g. ofmethyl 6-deoxy-6-iodo-lthio-a-D-galactopyranoside 2,3,4-tri-O-acetate (V), 4.6 g. of NaNO and 4.6 g. of phloroglucinol in 300 ml. of dimethylformamide was warmed at 65 C. (bath temp.) for 18 hours. The solvent was evaporated in vacuo. The residue thus freed of solvent was parti- VIAe - tioned between methylene chloride and water. The or- METHODA HOE CHzNOz HNO: HO 9 HO l SMe l SMe H VIH H v11 Methyl 6-deoxy-6-nitro-l-thio-a-D galactopyranoside 2,3,4-tri--acetate (VIAc) (2.19 g.) was suspended in 90 ml. of methanol and under N 0.7 ml. of a 25 percent solution of sodium methoxide in methanol was added over about 5 minutes. Dissolution was complete and the mixture tested basic to indicator paper. Tlc (chloroform-methanol, 6:1) showed hydrolysis to methyl 6-deoxy-6-nitro-l-thio-a-D-galactopyranoside (VII-l). Acetaldehyde (1 ml.) and 0.2 ml. of a 25 percent solution of sodium methoxide in methanol were added, followed in 10 minutes by 1 ml. more acetaldehyde and 3 more drops of the sodium methoxide solution. The methanol solution was treated successively with 2 portions of 10 g. of Dowex-SOresin (a cross-linked polystyrene nuclear sulfonic acid cation exhanger). The methanol was evaporated and the residue chromatographed over 1.1 kg. of silica gel using chloroform-methanol (6:1 as the solvent system. After a forerun of 500 ml., successive 10-ml. fractions were collected. Fractions through 39 were pooled and evaporated to dryness yielding 470 mg. (32,9 percent) of crystalline methyl 6-deoxy-6-nitro-l-thio-a-D- galactopyranoside (VII-l), M* 239. Fractions 49 through 78 were pooled and evaporated to dryness yielding 547 mg. (32.2 percent) of crystalline methyl 6- deamino-6-nitro-a-thiolincosaminide and its 7-epimer (VII), M? 283.

METHOD B In the manner described in method A, the 470 mg. of methyl 6-deoxy-6-nitro-l-thio-a-D-galactoside (VIH) of method A was condensed with acetaldehyde in methanol in the presence of sodium methoxide. After chromatography 280 mg. of crystalline methyl 6- deamino-6-nitro-a-thiolincosaminide and its 7-epimer (VII) (50.3 percent) was obtained.

Part II: Methyl a-thiolincosaminide and its 7-epimer (VIII) methyl 6-deamino-6-nitrol -thio-a-lincosaminide and its 7-epimer (VII) (220 mg.) from part G was dissolved in 3 ml. of tetrahydrofuran and added to 200 mg. of lithium aluminum hydride in 5 ml. of tetrahydrofuran. The reaction mixture was stirred for 0.5 hour at 20 C. and heated a reflux for 0.75 hour with cooling. A few drops of water were added and the mixture filtered. Evaporation of the filtrate gave only 9 mg. of an oil. The filtration residue was washed well with water and lyophilized. It was then chromatographed over 20 g. of silica gel using methanol as the solvent system. After a forerun of 40 ml., successive 2-ml. fractions were collected. Fractions 2 through 14 were pooled and evaporated to dryness yielding 14 mg. of material containing methyl a-thiolincosaminide and its 7-epimer (VIII).

Part I: Lincomycin (IXa) and its 7epimer To a solution of 63 mg. (0.3 mmole) of trans-lmethyl-4-propyl-L-2-pyrrolidinecarboxylic acid hydrochloride and 84 mg. of triethyl amine in 6 ml. acetonitrile was added 42 mg. of isobutyl chloroformate with cooling in an ice-methanol bath. To this solution there was added a solution of 58 mg. of crude methyl a-thiolincosaminide and its 7-epimer (VIII), prepared according to part B, in 3 ml. of water. After stirring for 1 hour the reaction mixture was evaporated to dryness in vacuo and the residue taken up in methylene chloride. The methylene chloride extract after filtering over anhydrous sodium sulfate was evaporated to dryness yielding about mg. of crude lincomycin. The crude lincomycin was chromatographed over 15 g. of silica gel using chloroformmethanol (4:1) as the solvent system. After a 40 ml. forerun, l-ml. fractions were combined. Fractions 2, 3, and 4 were pooled and evaporated to dryness yielding a product containing both lincomycin and its 7-epimer. Fractions 5 through 19 were pooled and evaporated to dryness yielding 6 mg. crude lincomycin as an oil. This was converted to hydrochloride and crystallized from aqueous acetone to yield crystalline lincomycin hydrochloride.

By substituting the acetaldehyde by other aldehydes compounds of the formula where- Ac ishydrogen or trans-l-methyl-4-propyl-L-2- pyrrolidinecarboxacyl (Pl-IA), Me is methyl, and R is the radical of the aldehyde RCHO are obtained. Thus, for example, formaldehyde gives methyl 6-deamino-6- nitro-8-nor-athiolincosaminimde, methyl 8-n0rathiolincosaminide, and 8-nor-lincomycin; propionaldehyde gives methyl 6-deamino-6-nitro-8-methyl -atriolincosaminide, methyl 8-methyl-a-thiolincosamideamino -6-nitr0-7-demethyl-7-phenyl-a-thiolincosaminideg methyl 7-demethyl-7-phenyl-a-thiolincosaminide, 6-deamino-6-nitro-7-phenyl-a-thiolincosaminide, and 7-demethyl-7-phenyl-lincomycin (R phenyl) and their 7-epimers; salicylaldehyde gives methyl 6-deamino-6-nitro-7-demethyl-7-(Z-hydroxyphenyl)-a-thiolincosaminide, methyl 7-demethyl-7-(2 hydroxyphenyl)-a-thiolincosaminide, and 7-de 7-(Z-hydroxyphenyl)-lincomycin (R 2-hydroxyphenyl) and their 7-epimers; tolualdehydes give methyl 6- deamino-6-nitro-7-demethyl-7 (o-, m-, and p-tolyl)-athiolincosaminide, methyl 7-demethyl-7-(o-, m-, and ptolyl)-a-thiolincosaminide, and 7-demethyl-7(o-g m-, and p-tolyl)-lincomycin (R tolyl) and their 7- epimers; nitrobenzaldehydes give methyl 6-deamino-6- nitro-7-methyl-7-(o-, m-, and p-nitrophenyl)-a-thiolincosaminide, methyl 7-demethyl-7-(o-, m-, and pnitrophenyl)-ot-thiolincosaminide, and 7-demethyl-7- o-, m-, and p-nitrophenyl)-lincomycin (R nitrophenyl) and their 7-epimers; and vanillin gives methyl 6- deamino-6-nitro-7-methyl-7-(3-methoxy-4-hydroxyphenyl)-a-thiolincosaminide, methyl 7-demethyl-7- (3'methoxy-4-hydroxyphenyl)-a-thiolinco- 7-dernethyl- 7-( 3-m ethoxy- 4-hydroxyphenel )-lincomycin (R 3-methoxy-4-hydr0xyphenyl) and their 7- epimers.

where R is hydrogen or lower-alkyl and R is lower alkyl, for example as disclosed in US. Pat. No. 3,380,662, compounds of the formula 0 H XII where Me is lower alkyl, R is lower-alkyl, phenyl, nitrophenyl, hydroxyphenyl, tolyl, or 3-methoxy-4- hydroxyphenyl, R is hydrogen or lower-alkyl and R" is lower-alkyl are obtained.

All the above compounds where Ac is an L-2-pyrrolidine carboxacyl have antibacterial activity like lincomycin and 7-epi-lincomycin and can be used in a like manner as lincomycin and 7-epi-lincomycin.

They can also be converted to the 7-deoxy-7-halo compounds by the processes given in US. Pat. No. 3,496,163 granted Feb. 17, 1970, and thus yield compounds of the formula where X is chlorine, bromines or iodine and Ac and Me are as given above which also have antibacterial activitylike lincomycin and 7-epilincomycin and can be used in a like manner as lincomycin and 7-epilincomycin. V

The compounds can exist in either the protonated or nonprotonated forms according to the pH of the environment and exist in stable acid addition salts, which are useful for the same purposes as the free bases, with the various acids as more particularly enumerated in the patents referred to above.

I claim: 1. A compound of the formula AcNH- l Me where R is lower-alkyl of more than two carbon atoms, phenyl, hydroxyphenyl, methoxyphenyl, nitrophenyl, or tolyl, Me is lower-alkyl, X is hydroxy, chlorine, bromine, or iodine, and Ac is hydrogen or an acyl radical of the formula wherein R is hydrogen or lower-alkyl and R" is loweralkyl, and acid addition salts thereof.

3,692,767 9 Ill 2. A compound of claim 1 in which Ac is hydrogen. under conditions effecting an aldol type condensation 3. A compound of claim 1 in which Ac is an acyl to formacompound of the formula radical as defined in claim 1.

4. A process for making compounds of the formula R 5 JOH- R N02- a OH HO where Me is lower-alkyl and R is the radical of the al- OH dehyde RCHO, subjecting the resulting compound to where R is the radical of an aldehyde RCHO, Me is Is lithium aluminum hydride reduction to form a comlower alkyl which comprises reacting a compound of Pound ofthe fm'mula the formula R N02 OH I AcO O NH/ 0 Ho o 0A0 SMe I CHzNO Ac ()(l i OH 0A0 where R and Me are as given above and wherein RCHO SMe IS an alkanol of not more than six carbon atoms, benzal- Ac dehyde, tolualdehyde, salicylaldehyde, nitrobenzalwhere Ac is hydrogen, acetyl, or benzoyl and Me is dehydeor vamhn' lower-alkyl with an aldehyde of the formula RCHO UTflTED STATES PA'IENT OFFICE CERTIFICATE OF CORRECTION Patent No. 5, 9 ,7 7 Dated September 19, 1972 Inventor(s) Barney J Magerlein It is certified that'error appears in the above-identified patent and that said Letters Patent are. hereby corrected as shown below:

Column 2, l ine 10, for pyrrol idinecarboxamide" read pyrrol idinecarboxamido line 19, for "plug" read plus l ine 58, for "pyrrol idinecarboxamide" read pyrrol idinecarboxamido Column l, l ine 7, for "through h 26" read through 26 line-8, for "dryness methyl read dryness ielding methyl l ine '48, for '6-NO-" read 6-0- l ine 8, for "toluensulfonyl--D-" read toluensulfonyl)-l-thio-o- D- l ine 62, for "(82%" read (82%) Column 5, l ine E for "(52,9%) read (32 9%) Col umn 6, l ine 25, for "a reflux read at reflux Column '7, l ine 19, for "trio- 1 incosaminide" read thiol incosaminide l ine 28, for "anc (-methylbutyl read and-B-methylbutyl l ine 28, for "and 80(" read and 8-( l ines 31-32, for "thlol incosaminideg" read thiol incosaminide l lnes 35-34, for "-thi l incosaminide, 6-deamino-6-nitro-T-phenyl a-thiol incosaminide and" read thlol incosaminide, and l ine 38, for "7-de" read 7-demethyl line l}, for "(o-g m-," read 0-, m-, l ine 55, for "thlol inco-" read thiol incosaminide and l ine 5%, for "phenel" read phen-y'l Column 8, l ine 35, for "bromines" read bromine --.Column 9, the structural formulas should appear as shown below instead of as in the patent.

FORM po'wso (L692 USCOMM-DC eoava-ps UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 5, 692,767 Dated September 19, 1972 Inventor(s) Barney J Maqer 1 e in 2 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

OH SMe H NO Ac 0 I I AC SMe OAc' Signed and sealed this 20th day of February 1973.

(SEAL) Attest:

EDWARD M.PLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents Q U 5 GOVERNMENT PRINTING OFFICE 1 I969 0-365-31 

2. A compound of claim 1 in which Ac is hydrogen.
 3. A compound of claim 1 in which Ac is an acyl radical as defined in claim
 1. 4. A process for making compounds of the formula 